This application relates to the field of identification cards for use in access control systems and, more particularly, to identification cards which are capable of being read by two or more different types of card readers.
Numerous types of identification cards are known in the access control field for storing identification data, and making this data available to card readers. The data may be placed on the cards in a variety of formats. One popular format uses a technology referred to as a magnetic stripe. In that format, the data is magnetically encoded sequentially along a strip of magnetic material on a card. Another format provides data which is magnetically encoded at selected locations on a magnetic material embedded within the interior of a card. In both the magnetic stripe and magnetic material cards, the data stored on the card is retrieved by inserting the card into a reader that senses the magnetic fields representative of the data. Magnetic field sensors for detecting the card data are typically housed within a structure having a slot or channel, which receives the card and aligns the magnetically encoded region of the card with the magnetic sensor portion of the reader.
As was suggested above, many access control systems for maintaining the security of controlled areas currently use identification cards having identification data magnetically encoded on the card. In these systems, authorized persons having valid identification cards may gain access to a secured area by inserting the magnetic card encoded with their identification data into a slot of a card reader. The magnetically encoded data on the card is read and sent to a system controller that processes the data, authorizes or refuses entry, and based thereon, signals the security system to either lock or unlock the door. This type of system is commonly referred to as an insertion system, since access is gained by inserting the identification card into a reader having magnetic field sensors. An example of such a system is described in U.S. Pat. No. 3,686,479 entitled "Static Reader System for Magnetic Cards." This patent and its disclosure are hereby incorporated herein by reference.
Also known in the access control field are identification tags or cards that contain electronic circuitry. The electronically stored data on these devices is often read remotely by means of radio-frequency transmission of signals between the identification card and a remote sensor. A common example of this type of identification device may also be found in clothing stores where the cards or tags are attached to the merchandise and a sensor is placed at an exit of the store. The sensor detects the identification card or tag if unauthorized removal of merchandise from the store is attempted. The electronically stored data on the card is read by positioning the card with respect to the sensor within a predetermined range and orientation. For example, in one typical application, the card may be read by the sensor if it is brought to within 12 inches of, and substantially parallel to, the front surface of the sensor.
Many access control systems incorporate this type of proximity card for use in maintaining the security of controlled areas. To gain access to a secured area with such an electronically encoded card, an authorized user need only present the card to a proximity sensor as previously described. The electronically encoded data on the card is communicated to the sensor by means of radio-frequency signals that propagate through the space separating the card and sensor. The card does not need to be physically inserted into the sensor. In other words, access may be gained merely by waving or placing the card in the general vicinity of the sensor as opposed to physically inserting the card into a specific slot or channel on the sensor. These types of sensors are known as proximity readers.
Since the proximity sensor and identification card do not have to physically touch one another in order to retrieve the identification data from the card, proximity sensors may be located in concealed locations. For example, the sensor may be embedded in or behind a wall. Thus, proximity sensors may be installed so that they are protected from outdoor weather conditions. Remote mounting further prevents vandals from tampering with the sensors. One example of a proximity system utilizing radio-frequency communication between an electronically encoded card and a remote sensor is described in U.S. Pat. No. 4,506,148 entitled "Identification Card." This patent and the disclosure therein are hereby incorporated herein by reference.
Prior to the advent of proximity access control systems, made possible by miniaturized electronics capable of being mounted in a card, most access control systems were of the insertion type described above. The insertion type systems have remained popular, and are often used when a facility which already has an insertion system is enlarged or expanded, since the compatible technology avoids problems of having insertion as well as another type of system on the same premises. However, proximity systems have also become quite popular and are often installed in new facilities which do not have any other types of access control systems.
In today's active business world where acquisitions and mergers are an everyday phenomenon, it is not unusual for a business to suddenly end up owning one facility having an insertion type access control system and another facility having a proximity type access control system. This can create problems for those individuals needing access to each of those facilities. Specifically, such an individual is forced to carry at least two identification cards, one for use in the insertion system and another for use in the proximity system. Of course, this is not only an inconvenience for the individual, but also can be a rather substantial expense for the business if there are a large number of persons needing access to both facilities. For each such individual, the business must bear the expense of providing and maintaining inventory and security control of at least two cards containing substantially identical information.
Based on the above, it would be an important improvement in the technology to provide a single card which could be used to obtain access to facilities having either insertion or proximity access control systems. It would be a further improvement in the technology to provide such a card which could be used in presently existing insertion card readers. It would be a still further improvement in the technology to provide a method of producing such a card combining the magnetic storage medium of an insertion card with the electronic storage capability of a proximity card, while minimizing interference between the two contrasting yet complementary storage and retrieval technologies.